If you have uploaded that zip file to your hosting account, then just log on to cpanel from from your hosting provider's site then you will to see those uploaded file.
select that file and then click on extract button

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**This script was taken from [a] website, it worked like a charm for me, hope it saves your time also.
**Please change attached file's extension to ".php".

This script is very easy to use, Just upload the unzipper.php to your server (specifically inside the folder where you have the zip file to extract). Now, go to your browser and open the location of unzipper.php file.

You’ll see a select input box which contains a list of zipped files in the folder. You can select any file and click on unzip archive.
It will start working right away and display success message upon completion.

Thats all you need to do…
After it completes extraction, you’ll see a new folder in the folder where you had the zip file with name of the zip file. That’s the extracted folder!